Simplify?

core.rb

module Model
  module Core
    include ExtensionLadder
  end
end

extension_ladder.rb

module ExtensionLadder #yuk yuk

include Mongoid::Document
include Mongoid::Pagination

      # useful extras, see: http://mongoid.org/en/mongoid/docs/extras.html
include Mongoid::Paranoia # soft deletes
index { deleted_at: 1 }

include Mongoid::Timestamps
index { created_at: 1 }
index { updated_at: 1 }

include Mongoid::Tree
include Mongoid::Tree::Ordering
include Mongoid::History::Trackable

# ElasticSearch integration
# don't index group since they are only a structural construct
unless 'Group' == name
  include, Tire::Model::Search
  include, Tire::Model::Callbacks
  # index name is dynamically set to the mongoid database name
  index_name, Proc.new {Search.index_name}
end

# Generate MD5 fingerprint for this document
field :md5, type: Moped::BSON::Binary
index { md5: 1 }
set_callback :save, :before, :generate_md5

# Make :headings a readable class variable
class_eval %(class << self; attr_reader :headings end)

# Create rdf_types field and accessor
class_eval %(class << self; attr_reader :rdf_types end)
field :rdf_types

# Include default embedded vocabularies
embeds_one :dbpedia,  class_name: 'DBpedia',  cascade_callbacks: true, autobuild: true unless 'Group' == base.name
embeds_one :rdfs,     class_name: 'RDFS',     cascade_callbacks: true, autobuild: true

# add useful class methods
extend ClassMethods

# NB: This has to be at the end to overload Mongoid
extend FOCB
end